I. Field of the Invention
The present invention generally relates to the field of removing carbon dioxide and, collaterally with that removal, other pollutants from waste streams. More particularly, the present invention relates to removing carbon dioxide and other pollutants from waste streams through the absorption of carbon dioxide and other pollutants from flue-gas-like streams. It includes the co-generation of group-2 carbonate materials.
II. Description of Related Art
Considerable domestic and international concern in both private and commercial sectors has been increasingly focused over the last four decades on emissions from industries into the air. In particular, attention has been focused on the greenhouse gases that have the property of affecting the retention of solar heat in the atmosphere, producing a “greenhouse effect.” The greenhouse effect occurs when incoming heat from the sun is trapped in the atmosphere and hydrosphere of the earth, raising the average atmospheric temperature, ocean temperature, and other average temperatures of the planet, resulting in climatic change. The effect is generally agreed as an operating effect in the Earth's thermal balance, though the rates, the extent to which man's combustion of materials affects it and the extent, direction, and magnitude of the effect are debated. Despite the degree of debate, all would agree there is a benefit to removing CO2 (and other chemicals) from point-emission sources if the cost for doing so were sufficiently small.
Greenhouse gases are predominately made up of carbon dioxide and are produced by municipal power plants and large-scale industry in site-power-plants, though they are also produced in any normal carbon combustion (such as automobiles, rain-forest clearing, simple burning, etc.). Since the most concentrated point-emissions typically occur at power-plants across the planet, reduction and/or removal from those fixed sites is an attractive point to effect a removal-technology. Because energy production is a primary cause of greenhouse gas emissions, methods such as reducing carbon intensity, improving efficiency, and sequestering carbon from power-plant flue-gas by various means has been researched and studied intensively over the last thirty years.
Reducing carbon intensity involves the alternate use of non-carbon energy sources such as nuclear, hydroelectric, photovoltaic, geothermal, and other sources of electric power to reduce the percentage of power produced through exclusive carbon combustion. While each of these techniques of power-generation continues to gain in terms of total energy production, the projections of world electricity demand are expected to increase at rates faster than energy production from these methods. Therefore, carbon greenhouse gas emissions are expected to increase despite growth in non-carbon energy sources.
Improving efficiency has generally focused on techniques of improving the combustion of carbon through pre-combustion, decarbonization, oxygen-fired combustion, etc. by first decreasing the amount of CO2 produced and then oxidizing all potential pollutants as completely as possible. Also, the technique increases the amount of energy generated per carbon dioxide emission released for improved efficiency. While strides in this area have improved combustion efficiency, there is little more improvement to be extracted from this field of endeavor.
Attempts at sequestration of carbon (in the initial form of gaseous CO2) have produced many varied techniques, which can be generally classified as geologic, terrestrial, or ocean systems. These techniques are primarily concerned with transporting generated carbon dioxide to physical sites and injecting the carbon dioxide into geologic, soil, or ocean repositories. Each of these sequestering techniques involves large costs in preparing CO2 for transport, accomplishing the transport, and performing the injection into a “carbon bank.” As such, these techniques are generally not economically feasible and in many cases consume more energy than the original carbon produced.
Sequestration can also include several industrial processes which include scrubbing, membranes, lower-cost O2, and hydrates. However, each of these technologies suffer due to the capital plant costs raised to uneconomic levels, and the effect of CO2 capture on the cost of electricity is prohibitive. The referenced shortcomings are not intended to be exhaustive, but rather are among many that tend to impair the effectiveness of previously known techniques for removing carbon dioxide from waste streams; however, those mentioned here are sufficient to demonstrate that the methodologies appearing in the art have not been altogether satisfactory and that a significant need exists for the techniques described and claimed in this disclosure.